This invention relates generally to an electronic wristwatch with a manually operated stem operating a switch actuator inside the watch to control its operation, and more particularly to a wristwatch in which the stem may be removed from the wristwatch and reinserted without disassembling the watch. Such watches include an internal electronic circuit and a battery supplying power to the circuit. The circuit generally includes a quartz crystal timebase, an integrated circuit with a frequency divider chain for supplying low frequency timekeeping pulses, and means to display the time either by actuating segments on an electrooptic display, or by operating a motor and gear train to drive the hands of the wristwatch. Although the invention will be described in connection with the latter type of timekeeping display in the context of a quartz analog wristwatch, the invention is equally applicable to a timepiece with an electrooptic display.
Manually operated crowns with stem detenting springs for holding the stem in selected axial positions and permitting axial movement of the stem against spring pressure provided by a detenting spring are well-known in the art. Examples are illustrated in U.S. Pat. Nos. 3,678,682 and 3,707,840, both issued to Miyasaka; U.S. Pat. No. 4,034,553 --Wuthrich, 4,228,647 --Yajama, and 4,363,554 --Schaffner et al., these being merely exemplary. In such stem detenting devices, the grooves in the stem between detenting surfaces are circumferential and hence there is no way to remove the stem without disassembling the watch, so that the detent spring can be detached.
The prior art also includes push button switch actuators for electronic wristwatches, which have only one normal axial position and are pushed against a spring bias, examples being shown in U.S. Pat. No. 3,783,607 --Feurer, U.S. Pat. No. 4,031,341 --Wuthrich et al., and U.S. Pat. No. 4,400,095 --Namyslo.
It is also well-known in the art to manipulate an external crown to operate internal stem-detented switch actuators for electronic wristwatches, as are illustrated in U.S. Pat. Nos. 3,526,088 --Meitinger, 4,031,341 --Wuthrich et al., and 4,536,095 --Wuthrich et al., all assigned to the present assignee. The last named Wuthrich patent 4,536,095 employs a rocking contact switch with a detented stem comprising semicircular detent grooves on one side of the stem and a flat surface on the other side of the stem. The stem is removable by inserting a tool and relieving the spring pressure by actuating extension arm on the detent rocker contact spring.
In order to reduce the manufacturing cost of an electronic wristwatch, it is desirable to have as few parts to be assembled as possible and for each of the parts to perform several functions. The parts are preferably designed to facilitate assembly and disassembly.
Accordingly, one object of the present invention is to provide an improved electronic wristwatch with a detented stem and switch actuator.
Another object of the invention is to provide an improved detented stem which may be manually actuated without danger of it coming out of the watch, but which may be removed and reinserted at repair facilities without disassembling the wristwatch.
Still another object of the invention is to provide an improved internal switch actuator for selectively operating the circuit of an electronic wristwatch.
Another object of the invention is to provide an simplified removable stem and switch actuator for an electronic wristwatch having a minimum number of parts.